This press benefited from the cost-effective replacement of an aging transfer systemwith a new more capable front-and-rear-mount servo model.

Transfer Systems - Can Stampers Save By Buying New? (full screen)
By Lou Kren

Difficult times demand that sheetmetal stampers do whatever they can to prolong equipment life. But when do repairs and upgrades enter the realm of throwing good money after bad? That's a tough call, and making the right decision involves assessing just how much improvement is possible, and whether equipment will be flexible enough and maintainable enough to justify the work and expense of a rebuild. When the issue revolves around transfer systems, there are clues that point to a new servo setup as the best option.

American Tool Die & Stamping News asked Paul Stirrett, vice president of sales and marketing for Linear Transfer Automation, Barrie, Ontario, Canada, to comment on factors that tilt the decision toward purchase of a new servo transfer system.

"I've come across a lot of stampers with older transfer systems who were looking to repair or replace," said Mr. Stirrett. "And many of them are dealing with existing transfers-mechanical and servo-driven-that operate with less precision as the equipment ages. In addition, fingers may not adequately hold the parts. A combination of these problems results in transfer systems that do not run as quickly or as accurately as they once did."

The biggest problem with rebuilding an aging transfer setup is the dearth of components, according to Mr. Stirrett. Many older drive and control components are not supported or directly replaceable after five years, he said, and even when an older system can be rebuilt, run rates rarely reach those achievable when the machinery was new. Mr. Stirrett cited stampers who examined replacement of aging drives to improve transfer performance, only to find that the cost of system electronics would cost more than a whole new servo setup, before mechanical upgrades had even been considered.

New Servo Transfer for Stamper
One Tier One automotive stamper located in the Southeast United States recently faced the decision of whether to rebuild or replace a dated through-the-window servo transfer system with a new unit. The stamper's senior process engineer explained the decision-process for the company:

The existing servo transfer dated from the mid-1980s, tending a 1,250-ton Verson press. The original manufacturer had offered to support the rebuild components, but that would only have replaced obsolete technology with a fresher set of the same obsolete technology-no real gain there, the engineer explained. Another problem: The drive setup was custom-built, and replacing some components would mean adapting other components to fit-one option included replacing an AC motor, but it wouldn't match up with the DC bus system. A spaghetti network of adaptions seemed to be where this project was heading. Traveling such a path would mean a future of extended downtime for complicated repairs and replacements. Beyond that, control communication was via a 1,200 bit/sec. modem.

his slow data transfer required 2 to 3 min. just to load die-change parameters into the system. The relatively ancient communication technology could be replaced, as long as the stamper was willing to retrofit the entire proprietary control system.

On the mechanical side, the aluminum rails exhibited twist, sway and flutter, affecting repeatability as shovels moved heat-shield parts from station to station. In operation, the stamper had to "keep the transfer loose," to allow parts to wiggle their way into the stations-not an ideal way to ensure part quality hit after hit. The loose nature of part transfer led to costly die maintenance and scrap, according to the engineer.

Paul Stirrett, vice president sales and marketing Linear Transfer Automation, used the 2010 Fabtech stage to highlight video of new servo-driven-transfer installations. “Often times,” said Mr. Stirrett, “new transfer systems can save money while adding capabilities as compared to trying to rebuild aging transfers.”

"We usually had to shut down the job once an hour to deal with the misfeeds," he recalled.

In discussing options with Linear Transfer Automation, replacing the controls and electronics, without even considering the mechanical components, would cost as much as a new front-to-back servo transfer system. Then and there the decision was made.

The old transfer system enabled lift of 5 in., according to the engineer, while the recently installed Linear transfer could provide a 36-in. lift. The stamper decided to stay with shovels as opposed to grippers to tool the transfer, but with the new system the shovels could be set up and adjusted to hold tolerance without the need for extra wiggle room.

The new servo transfer system also opened up new part-job opportunities-an impossible option with the old system due to its customized nature and mechanical imprecision. Also, according to the engineer, the old transfer system was limiting the press capabilities, and could only run to 10 strokes/min. on most jobs-slowed by shutdowns due to misfeeds and maintenance. The new system runs at a steady clip of 12-15 strokes/min., with job changeovers dropping from 1-1.5 hr. to 25 min., due chiefly to improved transfer-system controls.

As this case history shows, buying new can make sense from a cost and capability standpoint while eliminating the headaches that rebuilds can bring.

Listing the Benefits of New
Summarizing, Mr. Stirrett lists a number of reasons why stampers may decide on buying new as opposed to rebuilding old:

• The stamper cannot find parts as electronic components become impossible to source (try to find parts for a 10-year-old laptop computer).
• Even if the electronic controls are addressed in a rebuild, there is no guarantee that the mechanical portion of the transfer system will be able to control the parts.
• A mechanical and controls rebuild may cost more than a new transfer system where run rates are guaranteed.
• A new servo transfer system provides the latest functionality, which often is not even available on the old system.
• A new system gives the stamper a showpiece, communicating to customers that the stamper is not afraid to invest in capital equipment.
• New write-down incentives contained in the most recent federal government stimulus bill only qualify for new equipment.